Gradually equipment has been developed, for example, shut-down devices which can be transported into, and parked, for either a short or a longer period of time, at an intended position in a pipeline. An example of such equipment is valves of the kind which are described in Norwegian patent application No. 862775. These are valves which are intended to be placed permanently in the pipeline when in ordinary operation and which automatically, or by signal can shut down the pipeline in the case of fracture or catastrophe situations on or in the vicinity of a platform.
From DE PS No. 3142768C2, a pipeline is known which transports inflammable gas, and into which, in the case of pipeline fracture or leakage, a shut-down mechanism can be inserted, in order to join the flowing medium and consequently cause insignificant damage. The known shut-down mechanism consists of a cylindrical body, which in the case of an accident is launched into the pipeline from a platform and which via the pressure from the pipeline medium, with a piston-like action, is passed through the pipeline. The shut-down device is attached to the pipeline in the vicinity of the leakage locality. This is achieved by means of remote controlled pressurised air vessels, placed inside the cylindrical body, which supply gas to a rubber pod which is situated in an external bushing against the pipeline wall and which keeps the shut-down device restrained in the pipeline. In this way, further flow of the medium to the leakage locality is prevented. When employing this shut-down device, considerable time is required until the shut-down device is led forward to the leakage locality, in the case of pipeline fracture or a leakage.
In the German patent application No. P 3610625.9, a shut-down device is described wherein the pipeline medium can flow through an open cylinder and a valve is arranged for the purpose of shutting off the flow of the pipeline medium. This shut-down device can be inserted into the pipeline prior to an arising leakage, and in the case of a pipeline fracture, the valve actuates an immediate closure of the pipeline's fluid flow. Under normal conditions, the pressure drop of the fluid medium across the valve when the valve cone is open, is utilized to create the shut-down device's power of adherence.
Similar barrier systems are described in the German applications Nos. P 3610624.0 and P 3610626.7.
From the German patent application No. P 3417865.1 a self-driven inspection and maintenance vehicle for pipeline systems is known comprising a vehicle body and a drive unit and where the vehicle body is resiliently supported against the internal surface of the pipeline. The vehicle body is designed as a rigid, tightly closed housing and is provided with a separate electrical power supply. On the frontal surface relative to the launching direction the vehicle carries a T.V.-camera and a source of light to provide the T.V.-camera sufficient visibility. This inspection and maintenance vehicle can only be launched into empty and pressureless pipelines.